1. Field of the Invention
The present invention relates to an improved flare pilot which is stable in high winds and other severe weather conditions.
2. Description of the Prior Art
A variety of apparatus for flaring combustible waste fluid streams have been developed and used heretofore. Such apparatus are often referred to as flare stacks. Flare stacks are commonly located at production, refining and other processing plants for disposing of combustible wastes or other combustible streams which are diverted during venting, shut-downs, upsets and/or emergencies. Flare stacks generally include continuously operating pilots (often referred to as pilot lights) and flame detection apparatus which are often located at the elevated open discharge end of the flare stacks.
While the flare pilots utilized heretofore have operated successfully during normal weather conditions, at the time of high winds and other severe weather conditions both the burning waste or other fluid being flared and the pilot flame have been extinguished which allows the waste or other fluid to be discharged directly into the atmosphere without being burned. The unburned waste or other fluid pollutes the atmosphere which can be harmful to plant, animal and human life.
In order for a continuously operating flare pilot to remain lit and continue to ignite the combustible fluid discharged from a flare stack during severe weather conditions such as those which exist in hurricanes, typhoons and other similar weather conditions, the flare pilot must remain lit at wind speeds up to 125 mph or more when combined with two inches or more of rainfall per hour. In addition, gases which are often used as fuel for flare pilots are typically made up of natural gas or propane or a mixture of hydrocarbon gases that may contain hydrogen. A flare pilot utilizing gases as fuel which contain hydrogen must be capable of burning the gases without flashback due to the presence of the hydrogen.
Thus, there are needs for improved ultra-stable flare pilots which remain lit in high winds and other severe weather conditions.
The present invention provides improved continuously operating flare pilots which meet the needs described above and overcome the deficiencies of the prior art. The continuously operating flare pilot of this invention is stable in high winds and other severe weather conditions including wind speeds up to 160 mph or more and rainfall of 2 inches or more per hour at fuel pressures ranging from about 4 to about 45 psig using natural gas or propane as fuel. In addition, the pilot will stay lit in a 160 mph or more wind without flashback when burning a fuel containing up to 40% hydrogen.
The continuously operating flare pilot of this invention is basically comprised of a fuel-air mixture discharge nozzle connected to a fuel-air mixture inlet pipe. A wind shield having a partially closed or open lower end is sealingly attached to the fuel-air mixture discharge nozzle or to the fuel-air mixture inlet pipe whereby a fuel-air mixture discharged from the fuel-air discharge nozzle enters the interior of the wind shield. The wind shield has an open upper end which includes an upstanding wall portion positioned at the front of the wind shield facing the open end of a flare stack. Ignition flames from within the wind shield of the flare pilot are discharged through the open upper end of the wind shield adjacent to the combustible fluid discharged from the flare stack. The wind shield further includes at least one opening in each of the opposite sides of the wind shield positioned at substantially right angles to the upstanding wall portion through which wind can flow into the interior of the wind shield. Means for igniting the fuel-air mixture discharged within the wind shield by the fuel-air discharge nozzle and for detecting the presence or non-presence of flame therein can optionally be connected to the wind shield or discharge nozzle.
In a preferred embodiment, the wind shield and the upstanding wall portion of the open upper end of the wind shield include a plurality of downwardly orientated openings therein through which rain and wind are discharged when blowing in a direction from the back to the front of the wind shield. The wind shield also includes a plurality of openings in each of the opposite sides of the wind shield positioned at substantially right angles to the upstanding wall portion through which wind can flow into the interior of the wind shield. Wind catching baffles are also positioned around the pluralities of openings in the sides of the wind shield and the openings are orientated so that the wind flowing therethrough is caused to flow downwardly towards the inside lower end of the wind shield. The flare pilot preferably also includes a perforated flame stabilizer positioned within the wind shield attached to and surrounding the fuel-air nozzle. Finally, when included as a component of the flare pilot, the means for igniting the fuel-air mixture within the wind shield and for detecting the presence or non-presence of flame therein are preferably a flame front igniting apparatus and an acoustic flame detecting apparatus.
It is, therefore, a general object of the present invention to provide an improved continuously operating flare pilot for igniting combustible fluids discharged from the open end of a flare stack which is stable in high winds and other severe weather conditions.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows when taken in conjunction with the accompanying drawings.